DDEC swap to MUI?

[divinerightstrip]

Hello all!

As many of you already know, I am on the search for a new engine for my Prevost bus! I currently have an 8V92 DD in there with a broken crank. It is DDECII.

I had been on a mission to find another DDEC engine like this one to swap into it, however, BK brought to my attention that you can actually swap an MUI engine as well with a few modifications, and there are several advantages (and disadvantages) to this.

With this new insight, I have began to broaden my engine search and have come across a mechanical engine relatively close to my home. I'd like to take a look at this engine soon, but I don't want to put the cart before the horse here, and make assumptions and decisions without having any real knowledge of what is required.

Thus, I would like to revisit JohnEd's question that he posed in my usual post (which has gotten a bit long and out of control!) in a new thread here, and ask if any of you have actually done this swap yourself, know of anyone who has, and lived to tell the tale? (or, can at least point me in the direction of some real information!)

Any and all is appreciated.
Thank you!
-DRT

PS, here are some engine photos for your enjoyment!

[luvrbus]

What transmission do you have behind the DDEC


good luck

[divinerightstrip]

Allison trans. Not sure on the model... can find out.

Thanks!

[RickB]

divinerightstrip

Having just went through what you are about to embark on there are a couple pieces of advice I would give you.

I personally would never buy a used motor again without being able to see it start and run. I would recommend that you do a cold start and pay attention to smoke of any color that it may put out and the duration of that smoke timewise.

I would do an oil sample.

I would pull the turbo and the intake manifold below it and get a look at the blower. I would pull the valve covers and get a good look at the heads I would take pictures off all of these things and post them here for folks to get a look at them.

I wouldn't buy a motor that had low oil pressure or was over the accepted limits of silica in the oil sample.

I would not buy a motor that has sat without running for more than two years.

To change out the bellhousing is about 8 hours at your local shop, it is a difficult job to do and while you or your mechanic has the bellhousing off I would do the rear seal and the idler gear, they will have to pull the front harmonic balancer off your current motor and put your bus motor mounts on it and since they are already there I would have them do the front seal as well. You have a great plus in that you have your old motor to scavenge parts off of, the engine cradle, oil cooler and water pump, flex plate will allhave to be switched from old to new motor

These are just my opinions based upon my current motor which has turned out to be junk, when my wife asked me what I would do differently those are the things I would change if I could have a do over. I am sure there are things in this list that others would disagree with but nonetheless it is my list based upon my own observations.

Keep in mind that there are alot of guys who know alot more about these motors than I do. My current situation is proof of that.



Rick

[luvrbus]

If you have the 740 or 754 like most had it not a big deal all you need is a air throttle it would be the easiest and modulator for the transmission all the parts you need other than the above to do the change over will be on the old engine.
If the donor engine doesn't have the all in one shut down you will need to get one they are cheaper than the skinner valve setup and better cost around 80 bucks at DD.
If your DDEC doesn't have Jake's I see the donor does so you will need wiring for it and I see it has belt driven alternator and the bus engine will probably have a gear driven one also looks like a new blower.  
Just a Sunday walk no big deal there to use that engine for replacement save your parts try not do a trade in and you may recoup some bucks for the DDEC stuff and other parts.
This only applies if the engine is good and do the samples for the oil 



good luck

[divinerightstrip]

I personally would never buy a used motor again without being able to see it start and run. I would recommend that you do a cold start and pay attention to smoke of any color that it may put out and the duration of that smoke timewise.

I would do an oil sample.

I would pull the turbo and the intake manifold below it and get a look at the blower. I would pull the valve covers and get a good look at the heads I would take pictures off all of these things and post them here for folks to get a look at them.

I wouldn't buy a motor that had low oil pressure or was over the accepted limits of silica in the oil sample.

I would not buy a motor that has sat without running for more than two years.

Rick,
Thanks so much for the advice.

It is currently still in a truck that is still in use. I understand the importance of witnessing the cold start - I definitely plan on this!

How does one go about getting an oil sample? Or, rather, once I take an oil sample from the engine, what do I do with it, where do I send it?

And I will gladly take pictures of the engine with the valve covers off if such a situation presents itself to me. I'll definitely keep you guys updated on my progress.

If you have the 740 or 754 like most had it not a big deal all you need is a air throttle it would be the easiest and modulator for the transmission all the parts you need other than the above to do the change over will be on the old engine.

So, you are saying that I could keep my current trans? That would be preferable in this situation, as his has some issues. But even in the case of other engines, I know (rather, I have been informed) that mine works well.

If the donor engine doesn't have the all in one shut down you will need to get one they are cheaper than the skinner valve setup and better cost around 80 bucks at DD.

sweet.

If your DDEC doesn't have Jake's I see the donor does so you will need wiring for it and I see it has belt driven alternator and the bus engine will probably have a gear driven one also looks like a new blower. 
Just a Sunday walk no big deal there to use that engine for replacement save your parts try not do a trade in and you may recoup some bucks for the DDEC stuff and other parts.
This only applies if the engine is good and do the samples for the oil

My DD has jakes, thankfully. As does this one. A spare set would be nice, as I have heard that these are weak points in the 92 series.

Alright, samples of the oil it is! I'm on it.

[Ed Hackenbruch]

Go to a Peterbilt or Cat or Freightliner shop and one of them will have a little bottle that you drain the oil into.  They will tell you how full it needs to be. Cost is around $20. Take the sample after the engine has warmed up. They will give you a printout of all of the info from the test. Keep it so you can compare it to the next sample you do so you can see if anything changes.

[Sean]

I know I said in the other thread I would answer you here, but others have mostly beat me to it.  I will just add a couple of points.

If you have a 748, that's an ATEC transmission, and the two computers will be connected to each other.  The ATEC program will be optimized for the DDEC mill.  If you change to a mechanical, you will need to get a different TPS (throttle position sensor) for the Allison.

As Clifford (luvrbus) says, keep all your accessories from the old mill to swap in.  You'll want the gear-driven alternator, for example.

I personally favor the DDEC engines, but I'm a geek.  You've already got the harnesses in place for it, and if it were my coach, I'd look to replace it with another electronic engine of the same vintage, especially if the engine will be run on multiple fuel blends.  That being said, you'll want to keep your existing ECM and program, so you would need to find an engine with a compatible parts list.

-Sean
http://OurOdyssey.BlogSpot.com

[johns4104s]

DRT
If I were you I would continue you quest for a MUI, follow Clifford's direction, he will not lead you wrong.

John

[Busted Knuckle]

I would find a donor bus to get a matched engine/trans combo with accessories for an easier swap!

Try to avoid the truck to bus conversion situation it can be a headache in it's own! (don't ask how I know this!)
FWIW   BK 

[robertglines1]

consider $ before making decision...I have a 8v92 now 5 mpg...for under 10 grand can go 60 series with eaton with 8 plus mpg.consider the long run..does it have a hubometer on it? normaly changed when engine is rebuilt...could give you some ideal how many miles transmission has on it...or ck for rebuilder tag or stamp on trans..just trying to help with replace or improve ? best wishes...

[johns4104s]

Robert,

5mpg, That's what I get with my 8v92T at 60 mph.

John

[robertglines1]

sort of effects usage at 5 mpg vs 8 plus....if initial cost is main factor take Ricks and sure everyone else advice make sure you get a good used engine(8v92)..let a pro Detroit type (mech) evaluate it might save big bucks later for a little now.by the way my build sheet on the 89 prevost says transmission is a 755 Allison..I really don't understand the number system on Allisom trans.

[luvrbus]

A 755 is electronic 5 speed that may create a problem on the manual engine conversion 


good luck

[TomC]

Using an electronic transmission with a mechanical engine isn't that big of a deal. You just have to get a electronic throttle position sensor to have the ATEC Allison transmission work.  While it isn't as accurate as having both the DDEC and ATEC talking to each other, it does work.  Personally- I like having everything mechanically operated.  Then there are only two reasons a mechanical engine doesn't work-either it isn't getting fuel, or it has had a major mechanical catastrophe.  As compared to the DDEC engine that can have a oil pressure sensor, water temp sensor, water level sensor, exhaust temp sensor, accelerator pedal failure, wiring problems, wiring connector problems, wiring to the injectors, electrical shutdown, engine not talking to the transmission, transmission oil pressure, transmission oil temperature, transmission shifter failure-just a few items that can shut down an electronic engine/transmission.  Fun!  Good Luck, TomC